scholarly journals Ridge resonators: Impact of excitation beam and resonator losses

2021 ◽  
Author(s):  
Steffen Schoenhardt ◽  
Andreas Boes ◽  
Thach Nguyen ◽  
Arnan Mitchell
Keyword(s):  
Excitation Beam

scholarly journals Manipulating the surface-enhanced Raman spectroscopy (SERS) activity and plasmon-driven catalytic efficiency by the control of Ag NP/graphene layers under optical excitation

Nanophotonics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1529-1540
Author(s):  
Xianwu Xiu ◽  
Liping Hou ◽  
Jing Yu ◽  
Shouzhen Jiang ◽  
Chonghui Li ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Hot Spot ◽  
Catalytic Efficiency ◽  
Surface Enhanced Raman Spectroscopy ◽  
In Situ Monitoring ◽  
Excitation Beam ◽  
Graphene Layers ◽  
Cu Film ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Abstract Highly efficient plasmon-driven catalysis and excellent surface-enhanced Raman spectroscopy (SERS) performance are proportional to the square of the local electromagnetic field (hot spot). However, a proven way to realize the enhancement in intensity and density of “hot spot” still needs to be investigated. Here, we report on multilayered Ag nanoparticle (Ag NP)/graphene coupled to an underlying Cu film system (MAgNP-CuF) which can be used as an effective SERS substrates realizing ultra-sensitive detection for toxic molecules and in situ monitoring the plasmon-driven reaction for p-nitrothiophenol (PNTP) to p,p′-dimercaptobenzene (DMAB) conversion. The mechanism of ultra-sensitive SERS response and catalytic reaction is investigated via Ag NP/graphene layer-dependent experiments combined with theoretical simulations. The research found that the intensity and density of “hot spot” can be effectively manipulated by the number of plasmonic layers, and the bottom Cu film could also reflect the scattered and excitation beam and would further enhance the Raman signals. Moreover, the MAgNP-CuF exhibits outstanding performance in stability and reproducibility. We believe that this concept of multilayered plasmonic structures would be widely used not only in the field of SERS but also in the wider research in photocatalysis.

Laser Spectrofluorimetry of Chlorophylls

1974 ◽  
Vol 52 (22) ◽  
pp. 3723-3727 ◽  
Author(s):  
Roger M. Leblanc ◽  
Geneviève Galinier ◽  
Alain Tessier ◽  
Lise Lemieux
Keyword(s):  
Chlorophyll A ◽  
Emission Spectra ◽  
Polarization Rotator ◽  
Excitation Beam ◽  
Solid States ◽  
Set Up

A device has been set up to determine quantitatively the weak fluorescence intensities of pigment molecules. It consists of a laser spectrofluorimeter. The excitation beam can be produced with either a He/Cd laser (441.6 nm) or a He/Ne laser (632.8 nm). This system allows us to detect the fluorescence of dilute chlorophyll a or b solutions of the order of 10−12 mol/l. This sensitivity also permits the study of the emission spectra from chlorophyll in monomolecular or solid states, and since a polarization rotator has been incorporated into our apparatus, one may presume some possible orientation of the molecules.

scholarly journals Analysis of dynamics of a vertical cantilever in rotary coupling to the moving frame with movement limiters

2018 ◽  
Vol 241 ◽  
pp. 01021
Author(s):  
Piotr Wolszczak ◽  
Grzegorz Litak ◽  
Krystian Lygas
Keyword(s):  
Mechanical Energy ◽  
Elastic Beam ◽  
Beam Deflection ◽  
Moving Frame ◽  
Nonlinear Phenomena ◽  
Horizontal Distance ◽  
Energy Effect ◽  
Cross Sectional ◽  
Excitation Beam ◽  
Analysis Of Dynamics

The efficiency of the mechanical energy harvesting with the use of vibrating elements can be improved by synchronizing stimulation vibrations and own linear frequencies of systems as well as super or sub harmonics induced by non-linear phenomena. The article presents numerical cross-sectional study of the mechanical system. The system consists of an elastic beam set vertically, which the lower end is fixed in the rotary support, and is stimulated to move in the horizontal axis. The upper end of the beam is free but below its level there are bumpers limiting the free rotation of the beam. Numerical studies took into account the variability of the frequency and amplitude of the excitation beam movement, and horizontal distance between bumpers. Beam deflection was observed, on the basis of which the amount of energy generated by the piezo element was estimated. Nonlinear phenomena and analysis of frequency synchronization of vibrations improving the energy effect of an energy generator are presented.

High-Spatial-Resolution OH Rotational Temperature Measurements in an Atmospheric-Pressure Flame Using an Indium-Based Resonance Ionization Detector

1995 ◽  
Vol 49 (5) ◽  
pp. 655-659 ◽  
Author(s):  
Giuseppe A. Petrucci ◽  
Denise Imbroisl ◽  
Robert D. Guenard ◽  
Benjamin W. Smith ◽  
Jame D. Winefordner
Keyword(s):  
Temperature Profile ◽  
Spatial Resolution ◽  
Atmospheric Pressure ◽  
High Spatial Resolution ◽  
Rotational Temperature ◽  
Resonance Ionization ◽  
Excitation Spectra ◽  
Excitation Beam ◽  
Flame Region ◽  
Collisional Ionization

The use of a resonance ionization photon detector (RID) is described for the measurement of flame temperatures with a spatial resolution of less than 100 μm. The detector, based on the two-step excitation of indium atoms, with subsequent collisional ionization, was used to record rotational excitation scans of OH in an atmospheric-pressure acetylene/air flame. The OH excitation spectra were recorded by scanning an “excitation” laser in the A2σ+ ← X2II i (1, 0) vibronic band in the wavelength range, 281–288 nm, while simultaneously illuminating the same flame region with the “detection” laser, tuned to the 6 p2 P3/2 → 10 d2. D5/2 excited-state transition of In at 786.44 nm. The excitation and detection laser beams were made orthogonal in the flame, defining the resolution to be limited by the waist of the excitation beam (100 μm), whose diameter was always smaller than the detection laser beam. A temperature profile of the flame is recorded with the use of both the RID approach and a more conventional laser-induced fluorescence (LIF) approach for comparison. A more structured temperature profile is recorded with the RID owing to its high spatial resolution, whereas the LIF method, which is inherently a line-of-sight method, produces a rather featureless temperature distribution across the flame. Anomalously high flame temperatures were recorded at the flame edge with the RID. The cause of these high flame temperatures has not been determined.

scholarly journals Light-fuelled freestyle self-oscillators

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hao Zeng ◽  
Markus Lahikainen ◽  
Li Liu ◽  
Zafar Ahmed ◽  
Owies M. Wani ◽  
...  
Keyword(s):  
The Self ◽  
Stimuli Responsive ◽  
Sea Waves ◽  
Beam Position ◽  
Responsive Materials ◽  
Excitation Beam ◽  
Practical Applications ◽  
Oscillation Phenomenon ◽  
Oscillation Modes ◽  
Oscillation Dynamics

Abstract Self-oscillation is a phenomenon where an object sustains periodic motion upon non-periodic stimulus. It occurs commonly in nature, a few examples being heartbeat, sea waves and fluttering of leaves. Stimuli-responsive materials allow creating synthetic self-oscillators fuelled by different forms of energy, e.g. heat, light and chemicals, showing great potential for applications in power generation, autonomous mass transport, and self-propelled micro-robotics. However, most of the self-oscillators are based on bending deformation, thereby limiting their possibilities of being implemented in practical applications. Here, we report light-fuelled self-oscillators based on liquid crystal network actuators that can exhibit three basic oscillation modes: bending, twisting and contraction-expansion. We show that a time delay in material response dictates the self-oscillation dynamics, and realize a freestyle self-oscillator that combines numerous oscillation modes simultaneously by adjusting the excitation beam position. The results provide new insights into understanding of self-oscillation phenomenon and offer new designs for future self-propelling micro-robots.

Two-Photon Microscopy of Single Molecules

2000 ◽  
Vol 6 (S2) ◽  
pp. 802-803
Author(s):  
J. T. Fourkas ◽  
M. J. R. Previte ◽  
R. A. Farrer ◽  
C. Olson ◽  
L. A. Peyser
Keyword(s):  
Near Field ◽  
Single Molecules ◽  
Three Dimensional ◽  
Excitation Beam ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Higher Power ◽  
Excitation Techniques ◽  
Field Excitation ◽  
Heterogeneous Ensemble

The ability to observe the fluorescence arising from single molecules has revolutionized our ability to study the structure and dynamics of materials on a microscopic level and to probe the properties of individual members of a heterogeneous ensemble. A variety of near-field and far-field excitation techniques have been employed to study single molecules. Multiphoton excitation (MPE) techniques have a number of advantages that make them particularly attractive for singlemolecule detection. First, because the excitation and fluorescence wavelengths are significantly different from one another, Rayleigh and Raman scattering can easily be filtered out, leading to a low number of background counts. Second, because the probability for MPE depends on the excitation intensity to the second or higher power, the excitation is localized to the point in space where the excitation beam is most tightly focussed, thus providing three-dimensional resolution.

scholarly journals AN IMPROVED MICROFLUORIMETER FOR MEASURING BRIGHTNESS OF FLUORESCENT ANTIBODY REACTIONS

1967 ◽  
Vol 15 (1) ◽  
pp. 38-45 ◽  
Author(s):  
MORRIS GOLDMAN
Keyword(s):  
Continuous Monitoring ◽  
Bacterial Contamination ◽  
Fluorescent Antibody ◽  
Standard Errors ◽  
Microscope Slide ◽  
High Reproducibility ◽  
Excitation Beam ◽  
Virus Particles ◽  
Beam Output ◽  
Intermittent Measurements

A microfluorimeter suitable for measuring fluorescence of objects as small as bacteria is described. It consists of a fluorescence microscope equipped with one photomultiplier for intermittent measurements of observed objects, and another for continuous monitoring of the excitation beam. Output of the two photomultipliers is presented on a recorder as a ratio of the two currents. The light source is a high pressure mercury arc operated on de, and the instrument is aligned and standardized with the help of a standard fluorescent crystal mounted on a microscope slide. Measurements of intestinal amebae stained with a refined fraction of fluoresceinlabeled globulin showed high reproducibility on duplicate smears in spite of the presence of gross bacterial contamination. Standard errors of the means obtained from samples of 30 amebae averaged 5.6% of the means. The technique is capable of revealing extremely fine immunological distinctions in antigenic materials like intact microorganisms, virus particles and the like, even in the presence of tissue cells and other "contaminant" debris.

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